The objective of this work is to characterize the microscopic kinetics of the excitable tissues of nerve and muscle through the use of both electrical and optical probes. These experiments will quantitatively describe the previously reported multi-state sodium conductance as well as the nature of the potassium conduction states. In order to characterize the presumed gating charge for these conductances, complex admittance measurements of the asymmetry currents will be made. Finally, optical fluctuations from the myofilaments of contracting muscle will be measured to obtain kinetic information on the mechanisms of force generation. BIBLIOGRAPHIC REFERENCES: Moore, L.E., H.M. Fishman and D. Poussart. Identification of sodium ion conduction noise in the squid axon. Biophys. J. 17: 10a, 1977. Poussart, D,. L.E. Moore and H.M. Fishman. Measurement of the complex admittance of excitable membrane - an efficient method. Biophy. J. 17: 10a, 1977.